SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc7f5a0fa0816586dcfb746d7c968eaabe0e45830223bcf2a6c8784578ac4df6' 
  AND token = 'rPWNhUaBWTa+TRxf9CKe+4CvhyUoMyuVkgYLmPOtJG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}